In light-water nuclear reactors, the spacer grids made of zirconium alloy that retain the rods (fuel-containing tubes) form cells into which the rods are inserted and retained by assemblies of rigid means and resilient means.
These spacer grids are subjected to irradiation-induced growth, under the effect of which the dimensions of the cells are modified over the course of operation of the reactor. This modification makes the retention of the rods looser and looser, and the grids end up by no longer fulfilling their role satisfactorily.
It has been proposed in document EP-A-0 220 060 to produce these grids from a flat product made of a fully recrystallized zirconium alloy possessing a particular texture. This texture is such that the Kearns factors measured along the transverse direction and the longitudinal direction of the cell, when the grid is in place, are combined so that the irradiation of the grid during operation of the reactor causes a contraction of the cell and not an increase in its cross section. Thus, the clamping force exerted by the grid on the rods tends to increase instead of decrease.
It should be noted that document EP-A-0 220 060 does not propose a process for actually obtaining the desired texture. Processes for obtaining this texture are known, but they cannot be used because of major problems in the corrosion behavior of the reactor.